The present application is based on Japanese Application 2000-163101, filed on May 31, 2000, which is hereby incorporated by reference in its entirety.
1. Field of the Invention
This invention relates to an over lock sewing machine.
2. Discussion of the Background
Recently, a demand for a luxurious embroidery sewing machine has been increasing significantly according to a diversification of the individuals. In addition to a lock stitch sewing machine, a demand for an expansion of a zigzag decorative stitch type has been also increasing. Besides, as for an over lock sewing machine, a double-thread chain stitch bottom decoration function by a plurality of needles is added to comply with such demands. As a result, an application for making a decorative stitch with a seamy looper thread side has became popular.
In a general home sewing, the over lock sewing machine is suitable far a whipstitch but a zigzag stitch by the lock stitch sewing machine is substituted for the whipstitch instead of buying two different type sewing machines. In most cases, since a single lock stitch sewing machine is used for various purposes, a finish of stitching is inferior compared to that of a general clothing. Accordingly, in order to further improve the finish, it is general to purchase an over lock sewing machine as a second sewing machine taking account of a financial strain, a storage space, a work space, and a difficulty of an alternative usage. Further, in recent years, a knit material having large stretch has been used more and more. Accordingly, in a plain seam process, the finish of the double-thread chain stitch is superior to the finish of the lock stitch in most cases.
As a result, a technology which combines the functions of the lock stitch sewing machine and the over lock sewing machine has been developed. For instance, as a first conventional art, a sewing machine adding a lock stitch function to an over lock sewing machine is disclosed in a Japanese Patent Application published in 1996 as Toku Kai Hei 8-24451. The sewing machine is provided with a single needle bar and loopers and a shuttle body are positioned adjacent to each other.
As a second conventional art, a combined sewing machine is disclosed in a Japanese Patent Application published in 1981 as Toku Kai Sho 56-148378. The combined sewing machine is provided with an over lock function at a front surface of a leg portion of a lock stitch sewing machine. When in use of the over lock, the over lock function is moved to the lock stitch position.
As a third conventional art, a combined sewing machine is disclosed in a Japanese Patent Application published in 1979 as Toku Kai Sho 54-76347. The combined sewing machine is provided with an over lock function at a rearward of a leg portion of a lock stitch sewing machine. When in use of the over lock, the lock stitch sewing machine is inverted for using the over lock sewing machine.
However, the sewing machine in the first conventional art can make an over-edge chain stitch, a double-thread chain straight stitch, and a straight lock stitch but can not make a zigzag stitch. Various decorative stitches can not be achieved by the sewing machine. In the lock stitch sewing machine, the shuttle body is desirably positioned closest to a lower surface of a throat plate in order to assure the stitch function. In the conventional art, the shuttle body needs to be positioned lower than a bottom dead point of the over-edge chain needle in order to avoid the interference with the over-edge chain needle. Accordingly, the amount of the absorbing thread of the shuttle body is increased and the stitch function might be defected
Further, in proportion to the position of the shuttle body, the lower end of the lock stitch needle is positioned lower than the over-edge chain needle. When the same, type needles are used, the lower end of the needle holder holding the upper end portion of the needles also has the same step and the pressure increasing amount is limited in response to the step. In order to assure the pressure increasing amount with the over-edge chain needle, a special long needle in response to the step as the lock stitch needle needs to be used. When the long needle is used, the defects caused by a needle bend might be generated. Further, the threading the looper arranged at the rearward of the shuttle body might be difficult.
Moreover, a stroke of a needle thread take ups taking up the absorbing thread amount of the shuttle body is increased. Besides the increased stroke, the increase of the moving members might be a factor of a noise and oscillation malfunction. Further, materials such as a shuttle body, a needle thread take ups, a stitch balancing thread tension, and a sewing machine guide member for forming a seam of a lock stitch need to be added independently. As a result, the cost might be increased drastically.
The sewing machine in the second conventional art can make a straight lock stitch, a zigzag lock stitch, an over-edge chain stitch, and a double-thread chain straight stitch, but can not make a double-thread chain zigzag stitch. Various decorative stitches can not be achieved by the sewing machine. Further, materials such as a shuttle body, a needle thread take ups, a stitch balancing thread tension, and a sewing machine guide member for forming a seam of a lock stitch need to be added independently. As a result, the cost might be increased drastically. Moreover, a driving changeover clutch for the lock stitch and the over-edge chain stitch is added and the cost might be increased drastically. Further, when the over-edge chain stitch is made, the cloth feeding might be difficult due to materials such as a pressure foot and needles for the lock stitch provided at the rearward.
The sewing machine in the third conventional art can also make a straight lock stitch, a zigzag lock stitch, an over-edge chain stitch, and a double-thread chain straight stitch, but can not make a double-thread chain zigzag stitch. Various decorative stitches can not he achieved by the sewing machine. Further, materials such as a shuttle body, a needle thread take ups, a stitch balancing thread tension, and a sewing machine guide member for forming a seam of a lock stitch need to be added independently. As a result, the cost might be increased drastically. Moreover, a driving changeover clutch for the lock stitch and the over-edge chain stitch is added and the cost might be increased drastically.
Further, when the over-edge chain stitch is made, the sewing machine is difficult to operate since the sewing machine needs to be inverted.
It is an object of the present invention to provide an over lock sewing machine which can make various decorative stitches with the over-edge chain stitch function and the zigzag stitch function and which is low in cost.
In order to solve above technical problems, an over lock sewing machine for forming seams of an over-edge chain stitch and a double-thread chain stitch on a work cloth is provided with a needle bar holding a plurality of needles for forming a seam by a vertical reciprocating movement, a plurality of loopers and a needle bar transmitting mechanism moving the needle bar in approximately orthogonal direction relative to a cloth feeding direction of the work cloth and the vertical reciprocating direction of the needle bar.
According to an aspect of the present invention, since the needle bar can be moved in approximately orthogonality direction to the cloth feeding direction of the work cloth and the vertical reciprocating direction of the needle bar by the needle bar transmitting mechanism, the over lock sewing machine can make various decorative stitches with the over-edge chain stitch function and the zigzag stitch function. By only providing the needle bar transmitting mechanism, various decorative stitches can be realized. Accordingly, the over lock sewing machine can make various decorative stitches. The over lock sewing machine capable with operation as well as the conventional one can be obtained at a low cost.
In order to solve above technical problems, the over lock sewing machine is provided with the needle bar transmitting mechanism including an approximately T shaped needle bar holder having an approximately vertical portion vertically reciprocably supporting the needle bar at both end areas and an approximately horizontal portion extending perpendicularly from the middle of the vertical portion, a rack provided in parallel with the extending direction of the horizontal portion, and a worm connected with a rotating drive device fixed to a sewing machine frame and being in meshing engagement with the rack. The approximately horizontal portion of the over lock sewing machine is provided with a holding device being in parallel with the moving direction of the needle bar by the needle bar transmitting mechanism for slidably supporting a guide shaft fixed to the sewing machine frame at both end areas of the guide shaft.
According to another aspect of the present invention, the needle bar is vertically reciprocatably supported by the approximately vertical portion of the needle bar holder and the approximately horizontal portion can reciprocate in horizontal direction by the worm and the rack mechanism. Accordingly, since the needle bar transmitting mechanism can be configured with simple and compact structure, the over lock sewing machine can be obtained at a low cost. Further, since the needle bar can always be vertically reciprocatably perpendicularly supported by the approximately vertical portion, the generation of defects such as a stitch skipping and a thread breakage caused by a needle bend can be prevented.
In order to solve above technical problems, the over lock sewing machine is provided with the holding device including a plurality of boss portions extending from the both end areas of the horizontal portion and having a corresponding number of horizontal holes each having a common central axis extending in horizontally extended direction of the horizontal portion, a corresponding number of bushes for the guide shift inserted into the horizontal holes, and the guide shaft supported by the bushed, said holding device further includes a plurality of boss portions extending from the both end areas of the vertical portion and having a corresponding number of vertical holes each having a common central axis extending in vertically extended direction of the vertical portion, a corresponding number of bushes for the needle bar inserted into the vertical holes, and the needle bar vertically reciprocably supported by the bushels for the needle bar and wherein the horizontal holes and the bushes fur the guide shaft are adhered together and the vertical holes and the bushes for the needle bar are adhered together.
According to still another aspect of the present invention, the guide shaft bushes and the needle bar bushes can be adhered to the needle holder with keeping the perpendicularity therebetween by a tool. Accordingly, since the high accuracy to manufacture the needle bar holder is not needed, the needle bar holder can be manufactured at a low cost.
According to an aspect of the present invention, the over lock sewing machine is provided with the needle bar transmitting mechanism moving the needle bar in approximately orthogonality direction to the cloth feeding direction of the work cloth and the vertical reciprocating direction of the needle bar. The needle bar being synchronized with the movement of the loopers can move in approximately orthogonality right and left direction to the cloth feeding direction of the work cloth and the vertical reciprocating direction of the needle bar. Accordingly, the over lock sewing machine can realize the over-edge chain stitch function and the zigzag stitch function.
Accordingly, with a single sewing machine, a double-thread chain zigzag stitch as a substitution for a lock stitch sewing machine, and a decorative stitch as well as a zigzag decorative stitch type of the lock stitch sewing machine can be achieved besides an over-edge chain stitch. Further, an optimal stitch type for a kit material can be achieved. In this manner, high completion of home sewing can be realized for solving above technical problems.